Mask shell/assembly



FIG. 1 is a perspective view of a mask shell according to a first embodiment of our design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a top view thereof;

FIG. 5 is a bottom view thereof;

FIG. 6 is a left side view thereof;

FIG. 7 is a right side view thereof;

FIG. 8 is a perspective view of a mask assembly according to a second embodiment of our design;

FIG. 9 is a front view thereof;

FIG. 10 is a rear view thereof;

FIG. 11 is a top view thereof;

FIG. 12 is a bottom view thereof;

FIG. 13 is a left side view thereof; and,

FIG. 14 is a right side view thereof.

Where included, broken lines showing environment or structure are for illustrative purposes only and form no part of the claimed design. Where included, dotted lines represent the border between claimed and non-claimed subject matter and form no part of the claimed design.

Where included, the use of stippling is intended to denote shading. 

The ornamental design for a mask shell/assembly, as shown and described. 